CONICET | Buscador de Institutos y Recursos Humanos

Willow commercial genotypes areusually propagated as unrooted cuttings. During the establishment phase, the cuttingsare still developing their root system and leaf area, and are vulnerable to theoccurrence of stresses like flooding, leading to failure of new plantations. Inconsequence, it is relevant to identify traits correlating to floodingtolerance during the early growth of willows.We evaluated the floodingtolerance of plants obtained from cuttings of 29 genotypes from the collectionof the willow breeding program of INTA. The species included were Salixmatsudana, S. alba, S.nigra, S. jessoensis , S.amygdaloides, S. humboldtiana, S.viminalis, S.babylonica and the hybrids S.matsudana x S.alba, S. fragilis x S.alba and S. matsudana x S. nigra. Two-months old plants growing inpots in a greenhouse underwent two treatments: watered to field capacity(control) and flooded (80% of the stem covered by still water) for 41 days. Atthe end of the stress episode, different traits were measured: height, collardiameter, basic wood density, plant dry biomass and leaf area. A floodingtolerance index for each genotype was estimated as the percent ratio betweenflooded and control total biomass. There was ample variation in floodingtolerance, with the index ranging from 39% to 117%. Most clones had a reduced biomassaccumulation under flooding conditions and only 4 genotypes had similar orhigher biomass than control plants. The Pearson correlation coefficient wasestimated between the flooding tolerance index and the different variablesmeasured. Several traits had a positive and significant correlation withflooding tolerance: height (r=0.69, p<0.01), collar diameter (r=0.71,p<0.01), plant dry biomass (r=0.71, p<0.01), plant leaf area (r=0.49,p<0.01) and basic wood density (r=0.53, p<0.01). These traits are easy to measure and could beuseful to select for increased flooding tolerance in willows during the earlystages of growth.